AT390287B - Method and device for calendaring a paper sheet - Google Patents

Method and device for calendaring a paper sheet Download PDF

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Publication number
AT390287B
AT390287B AT0376185A AT376185A AT390287B AT 390287 B AT390287 B AT 390287B AT 0376185 A AT0376185 A AT 0376185A AT 376185 A AT376185 A AT 376185A AT 390287 B AT390287 B AT 390287B
Authority
AT
Austria
Prior art keywords
web
roller
nip
temperature
calendering
Prior art date
Application number
AT0376185A
Other languages
German (de)
Other versions
ATA376185A (en
Inventor
Ronald D Agronin
Paul J Klemmer
Original Assignee
Waertsilae Oy Ab
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to US06/688,650 priority Critical patent/US4606264A/en
Application filed by Waertsilae Oy Ab filed Critical Waertsilae Oy Ab
Publication of ATA376185A publication Critical patent/ATA376185A/en
Application granted granted Critical
Publication of AT390287B publication Critical patent/AT390287B/en

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Classifications

    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21GCALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
    • D21G1/00Calenders; Smoothing apparatus
    • D21G1/02Rolls; Their bearings
    • D21G1/0206Controlled deflection rolls
    • D21G1/0213Controlled deflection rolls with deflection compensation means acting between the roller shell and its supporting member
    • D21G1/022Controlled deflection rolls with deflection compensation means acting between the roller shell and its supporting member the means using fluid pressure
    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21GCALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
    • D21G1/00Calenders; Smoothing apparatus
    • D21G1/0073Accessories for calenders
    • D21G1/0093Web conditioning devices
    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21GCALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
    • D21G1/00Calenders; Smoothing apparatus
    • D21G1/02Rolls; Their bearings
    • D21G1/0233Soft rolls
    • D21G1/024Soft rolls formed from a plurality of compacted disc elements or from a spirally-wound band

Description

No. 390 287

The invention relates to a method for calendering a paper web in order to obtain a high gloss, smooth web of substantially constant density and with minimal marbling, in which method at least one nip is provided for each surface of the web to be calendered to form the nip one Steel roller and a compliant roller are used and the web is passed through each nip, and an apparatus for performing the method.

There are different types of calendering processes. One type, known as supercalendering, is to pass a web sequentially through a series of nips formed by pairs of iron rolls and filled rolls. The term supercalendering is used because there may be eight or more such nips through which the web passes. Supercalendering can give useful properties to the web, including improved gloss, density, smoothness and the like.

Another type of calendering is the single or double pass calender, in which relatively few nips are used by pairs of iron rolls, e.g. B. one or two nips. Such calendering is satisfactory for some types of paper, but is not suitable for producing paper with high gloss and high smoothness for quality printing

If possible, it would of course be preferred to guide a web through as few nips as possible in order to achieve the desired properties which are necessary for quality printing.

A web that passes through many nips becomes less and less suitable to tolerate additional processing without breaking, tearing, jumping, etc. As a result, it would be highly desirable to produce quality paper without the need to supercalender a web. In short, it would be desirable to produce a quality paper by a calendering process that only has a few nips, e.g. B. two or less

It is known from the prior art to calender a web with a temperature gradient in order to achieve improved gloss, smoothness, strength and ink transfer properties. This is described in an article by R.H. Crotogino, published in the October 1982 Tappi Journal, pages 97-101. The Crotogino article describes a calendering process in which a web is passed through two nips formed by heated iron rolls. The rollers are heated to a temperature of about 210 ° C (410 ° F). By temperature gradient calendering it is meant that there is a noticeable difference between temperatures to which the web surface and the web interior are exposed. Therefore, when a relatively cold web comes into contact with very hot iron rolls, there is a considerable temperature differential between the surface of the web and the inner part. When the web is compressed by the nips of the heated rolls, the hot outer web surface is deformed more than the interior, resulting in a smoother, glossier web that has higher strength and better ink transfer capability than webs that machine-calender at moderate temperature will. Crotogino claims that nip temperature gradient calendering approaches the quality achieved by supercalendering for smoothness and gloss

The Crotogino arrangement gives a constant web thickness, but not a constant density. The main reason is the rigidity of the heated iron rollers. The lack of density control results in the marbling of the web. Marbling means that deviations that are inherent to the web (high and low points) from the nip are not treated to the same extent. In this way, the high points become glossier and smoother than the low points, which are not exposed to the same temperature and pressure.

It is desirable to provide a method and apparatus which has the advantages of temperature gradient calendering - few nips - but which can produce high quality webs without marbling.

It is therefore an object of the present invention to provide an improved method and an improved device for temperature gradient calendering, which takes advantage of temperature gradient calendering, i. H. have few nips, at the same time producing a high quality web with constant thickness and little or no marbling.

It is a further object of the invention to provide a temperature gradient calendering process with two nips and an apparatus using a heated iron roll together with an unheated compliant roll, whereby both ropes of a web can be treated.

Another object of the invention is to provide a temperature gradient calendering method and apparatus using a spherical, compliant control roller to maximize the quality of the smoothing process.

The method for solving all of these problems is characterized in that a) that to compensate for web changes, roll wear, hot spots and the like. The profile of the compliant roll is changed by a hydraulic servo system with a pump for supplying oil to selected roll elements by one to ensure substantially constant web density and substantially eliminate marbling, and b) heating the steel roller to a temperature of at least 177 ° C sufficient to deform the surface fibers in the paper web but less than the temperature that is necessary to -2-

No. 390,287 to deform the inner fibers, thereby keeping the inner fibers relatively cooler and essentially unchanged. According to a further characteristic of the invention, the steel roller is heated to a temperature in the range from 177 to 200 ° C. According to the invention, in the device for carrying out the method, the flexible roller has a changeable profile, the steel roller being heatable.

The invention combines the advantages of supercalendering with the advantages of temperature gradient calendering, which means that relatively few nips are required to produce a web with improved gloss, smoothness and ink transfer properties, while at the same time providing qualities that are otherwise only achievable with supercalendering. This is achieved by using two pairs of rollers that form two nips (provided both sides of the web are to be treated). The first nip uses a heated iron roll and an unheated, compliant roll. The second nip has the same pair of rollers, but in the opposite position to treat the other side of the web. The iron rolls are heated to a temperature of at least 177 ° C (350 ° F); this is the approximate temperature at which cellulose fibers in the web begin to soften and deform. In a preferred embodiment of the invention, the compliant roller, which may be made of Nomex or other available resilient material, may include a zone control system. Zone control means that the spherical geometry can be changed to remove hot spots caused by changes in the web profile or in the rollers due to wear or damage.

The invention will now be described, for example, with reference to the drawings.

Fig. 1 is a representation of an education that occurs in the Crotogino article referred to in the basis of the description.

Figure 2 is a schematic diagram of an apparatus suitable for carrying out the method according to the invention.

Figure 3 is a view of a preferred embodiment of the invention using an adjustable, spherical, compliant roller.

Fig. 4 is a drawing indicating the manner in which the adjustable, spherical control roller works

The invention relates to temperature gradient calendering. This technique involves the use of high temperature rolls to calender the web, the temperatures being well above the temperature of the web prior to entering the calendering nip.

In standard calendering processes, whether machine calender or supercalender are used, the maximum working temperature is usually no more than 93 ° C (200 ° F). This temperature is generated by heating the iron rolls, which form at least one of the two rolls for each roll nip. In some cases, the steel roller faces a resilient roller that can become as hot or even hotter than the steel roller during prolonged operation of the calender. Machine calendering (few nips) cannot produce high gloss paper with constant density. If a higher gloss is desired, it is necessary to use a super calender with a large number of nips (on the order of 9 to 11) in order to achieve the desired result. However, this has an adverse effect on the mass and of course requires expensive machines in a secondary processing.

In contrast, the temperature gradient calendering uses only one or two nips, which can achieve a high gloss without loss of body. Furthermore, this can possibly be " on the machine " be carried out, d. H. directly when the web comes out of the papermaking machine and not during a second treatment of an existing web, as is the case with supercalendering. In temperature gradient calendering, one or both of the rolls forming a nip can be heated to a temperature of at least 177 ° C (350 ° F). This temperature is critical, but depends on the " flow temperature " of the respective fibers of the web. In order to achieve an effective temperature gradient calendering, the nip temperature must be sufficient for the surface fibers of the web to be deformed.

Temperature gradient calendering with two heated steel rollers is described in the mentioned prior art according to Crotogino. Fig. 1 is a reproduction of an image from the Crotogino reference and shows the temperature gradient difference between ordinary calendering and temperature gradient calendering. As can be seen from the left-hand side of the figure, the temperature difference between the calender rolls and the paper, as well as the temperature change over the thickness of the web, is small in the usual calendering. The nip pressure deforms the entire web evenly across its thickness as a result. A high gloss therefore causes many nips and results in a loss of web body.

In the case of temperature gradient calendering, the web is brought into contact with very hot calender rolls, the high temperature gradient shown being generated between the surface and the central part of the web. The nip pressure on the hotter surfaces of the web deforms it more than the central part of the web, which results in an improved gloss with little body loss

Crotogino is therefore an improvement because high gloss can be achieved with just a few nips. However, the Crotogino process with two heated steel rolls creates a web of constant thickness but not constant density due to the inevitable changes (high and low places) in the web. The Crotogino technology therefore, although it has a higher, medium gloss -3-

No. 390 287 produces a marbled sheet, in which some parts of the sheet are shinier than others. This effect can interact with the printing process by causing changes in the color transfer and ultimately the legibility of the paper.

According to the present invention, the advantage of high temperature calendering - higher gloss with fewer nips - but without marbling is achieved. The present invention uses at least one nip formed by a heated steel roller and an elastic or resilient roller. If only one side of the web needs to be calendered, a single nip is sufficient. If both sides of a web are to be calendered, two nips are required. If further web improvement is desired, paper calendering with three or more nips may be necessary.

To illustrate the invention, FIG. 2 shows a double roll nip arrangement for carrying out the invention. In Fig. 2 a support column (10) is provided with two pairs of rollers, which form a first nip (12) and a second nip (14) through which a web (16) passes. The nip (12) is driven by a heated steel roller ( 18) and an unheated, flexible roller (20) is formed. The nip (14) is similarly formed by a steel roller (22) and a resilient roller (24). However, it should be noted that the relative positions of the steel roller and the compliant roller are twisted so that both surfaces of the web (16) are treated. According to the invention, the steel rollers (18) and (22) are heated to the necessary temperature at which the fibers of the web surface begin to deform. This is in the approximate range of 177 ° C to 204 ° C (350 ° F to 400 ° F). The compliant rollers (20) and (24) can be made from a variety of elastic materials, such as. B. Nomex, paper-filled rollers and the like. They are not heated, although they get quite hot due to the heat transfer from the steel roller.

Because the compliant rollers adapt to changes in the web, the marbling effect according to the Crotogino technique is avoided. The present invention is suitable for producing a high gloss with a chosen, constant density. The gloss on the web is relatively even and the density of the web is essentially constant. With reference to the following table, comparison data for conventional supercalendering, the Crotogino method and the present invention are shown:

Table 1

Coated paper

Gardner shine felt_wire

Printing area (roughness)

Felt_ wire

Supeikalander (9 nips) 87 Crotogino 2 heated steel rolls (1 pass) 72 present invention 1 heated steel roll 1 compliant roll (2 passes) 82 82 1.21 1.59 70 1.90 2.20 81 1.47 1.69 - 4-

No. 390 287

Table 2 Newspaper printing

Gardner shine felt_wire

Print area (roughness) felt wire

Supeikalander (9 nips) Crotogino 2 heated steel rolls (1 pass) present invention 1 heated steel roll 1 compliant roll (2 passes) 27 35 26 24 33 35 2.13 2.06 3.47 3.51 2.41 2.40

As can be seen from the table, the present invention provides a product with excellent gloss and a Paiker coverage area (a measure of roughness). When looking at the data, it must be noted that accurate comparisons are difficult to make due to the difference in paper webs from sample to sample, slight differences in the examination procedures, and the error limitations of the measurement techniques. Nevertheless, it can be conveniently concluded from the data that the present invention provides an excellent web comparable to supercalendering and substantially better than the temperature gradient calendering obtained with Crotogino's technique while avoiding the marbling problem.

3 shows a preferred embodiment of the invention. In Fig. 3, the elements that are identical to Fig. 2 are similarly labeled. This embodiment of the invention uses specially designed, compliant rollers (30) and (32) which have variable circumferential control. Changeable circumferential control rolls can adjust their profile across the cross direction of the web to eliminate hot spots caused by uneven wear on the rolls, uneven loading (nip pressure), or other factors normally encountered during the calendering process. In the prior art, changeable rolls are usually steel rolls. However, for the purposes of the present invention, it is desirable to have a compliant roll with variable surface options. This is necessary because the existing changeable rolls cannot be heated to the high temperatures of 177 to 204 ° C (350-400 ° F) necessary to perform the temperature gradient calendering in accordance with the present invention.

As shown in Fig. 4, the compliant roller is a variable surface roller. Your profile is set by the operator as a function of a variable related to the quality of the web, such as B. the temperature profile over the nip, the thickness of the web after calendering, etc. The mechanism for adjusting the surface and the techniques for controlling the adjustment devices are known in the art, such as. See, for example, U.S. Patents 4,327,468 and 4,480,537, the latter of which is assigned to the assignee of the present application and which is incorporated by reference. In short, the mechanism has a hydraulic servo system with a pump for supplying oil to selected elements (40) to change the profile of the calendering surface (42) of the compliant roll.

In operation, the steel rollers (18) and (22) are preheated to the desired temperature of approximately 177 to 200 ° C (350-400 ° F). The web is then passed through the nips and exposed to the steel roller and the compliant rollers so as to smooth them while improving the gloss and smoothness of the web surface without significant body loss. Density is maintained substantially constant due to the ability of the compliant roll to adapt to web changes and compensate for web changes. This ability is brought to an optimum by using flexible rollers with changeable surface adjustment options. The resulting sheet has a high gloss and smoothness, a good body, constant density and of equal importance, marbling is not detectable.

The invention is not restricted to the embodiments shown and illustrated and can be modified without further ado. -5-

Claims (3)

  1. No. 390,287 PATENT CLAIMS 1. A method of calendering a paper web to obtain a high gloss, smooth web of substantially constant density and with minimal marbling, which method provides at least one nip for each surface of the web to be calendered to form the Roll gap a steel roller and a compliant roller are used and the web is passed through each nip, characterized in that a) that to compensate for web changes, roller wear, hot spots and the like. The profile of the compliant roller by a hydraulic servo system with a pump for Feeding oil to selected roller elements changes to ensure a substantially constant web density and substantially eliminate marbling, and b) heating the steel roller to a temperature of at least 177 ° C sufficient to remove the surface fibers in the Deform paper web, however is less than the temperature necessary to deform the inner fibers, leaving the inner fibers relatively cooler and substantially unchanged.
  2. 2. The method according to claim 1, characterized in that the steel roller is heated to a temperature in the range of 177 to 204 ° C.
  3. 3. Apparatus for carrying out the method according to claim 1, in order to achieve a high-gloss, smooth web of substantially constant density with minimal marbling, at least one nip being provided for the passage of the web to be calendered and the nip through a steel roller and a resilient roller is formed, characterized in that the resilient roller (20) has a changeable profile and the steel roller (18) is heatable. 2 sheet drawings
AT0376185A 1985-01-04 1985-12-27 Method and device for calendaring a paper sheet AT390287B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US06/688,650 US4606264A (en) 1985-01-04 1985-01-04 Method and apparatus for temperature gradient calendering

Publications (2)

Publication Number Publication Date
ATA376185A ATA376185A (en) 1989-09-15
AT390287B true AT390287B (en) 1990-04-10

Family

ID=24765218

Family Applications (1)

Application Number Title Priority Date Filing Date
AT0376185A AT390287B (en) 1985-01-04 1985-12-27 Method and device for calendaring a paper sheet

Country Status (6)

Country Link
US (1) US4606264A (en)
AT (1) AT390287B (en)
CA (1) CA1264588A (en)
DE (1) DE3600033A1 (en)
FI (1) FI74066B (en)
SE (1) SE466757B (en)

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US4749445A (en) * 1984-05-18 1988-06-07 S. D. Warren Company Method of finishing paper utilizing substrata thermal molding
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US5251551A (en) * 1988-09-29 1993-10-12 Jujo Paper Co., Ltd. Calendering apparatus for paper making process
US5156086A (en) * 1988-11-11 1992-10-20 Valmet Paper Machinery Inc. Method of calendering a paper web
DE3937246C2 (en) * 1988-11-11 2002-06-27 Metso Paper Inc calendering
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US5462594A (en) * 1990-04-19 1995-10-31 Valmet Paper Machinery Inc. Coating device for coating of a size-press roll, paper or board
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DE4124940A1 (en) * 1991-07-27 1993-01-28 Kuesters Eduard Maschf Paper web calender - has pairs of rollers to give a combined calibration and heat gloss application
DE4126233C1 (en) * 1991-08-08 1992-09-17 Sulzer-Escher Wyss Gmbh, 7980 Ravensburg, De
US5237915A (en) * 1992-02-04 1993-08-24 The Mead Corporation Mixed roll calender
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US5524532A (en) * 1994-12-28 1996-06-11 Valmet Corporation Method and apparatus for calendering a paper or board web
FI101985B1 (en) * 1996-12-10 1998-09-30 Valmet Corp Method and apparatus for drying a fibrous web
US6254725B1 (en) 1997-06-20 2001-07-03 Consolidated Papers, Inc. High bulk paper
US6274001B1 (en) 1997-10-21 2001-08-14 International Paper Company Method for calendering surface sized paper/paperboard to improve smoothness
FI112965B (en) 1999-11-05 2004-02-13 Metso Paper Inc Calendering arrangement for paper machine
FI115405B (en) * 2000-06-20 2005-04-29 Metso Paper Inc Calendering method especially for pre-calendering and paper processing line
FI115543B (en) * 2000-06-20 2005-05-31 Metso Paper Inc Procedure for preliminary calendering, post-processing and apparatus for carrying out the processes
AU1407602A (en) * 2000-11-09 2002-05-21 Metso Paper Inc Method for the manufacture of paper, in particular of coated fine paper, and a paper machine line in particular for the manufacture of coated fine paper
FI116402B (en) * 2001-04-17 2005-11-15 Metso Paper Inc Calendering
FI20011291A (en) * 2001-06-18 2002-12-19 Metso Paper Inc Process and paper machine for making coated paper
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US7036800B2 (en) * 2002-04-08 2006-05-02 Ellis Earle R Automatically controlling the interaction of a medium with an external environment
US20040123966A1 (en) * 2002-04-11 2004-07-01 Altman Thomas E. Web smoothness improvement process
US7335276B2 (en) * 2002-10-01 2008-02-26 E.I. Du Pont De Nemours And Company Formation of aramid paper laminate
FI20060670A0 (en) * 2006-07-10 2006-07-10 Mikko Kaira Method for increasing the bulk of a fiber product and manufactured fiber product
US20080070463A1 (en) * 2006-09-20 2008-03-20 Pankaj Arora Nanowebs
US9028036B1 (en) 2013-11-25 2015-05-12 Ricoh Company, Ltd. Edge-justified printing with a crowned roller
US9686540B2 (en) 2014-06-23 2017-06-20 Xerox Corporation Robust colorimetric processing method for paper based sensors
US9365019B2 (en) 2014-06-23 2016-06-14 Xerox Corporation Apparatus for forming hydrophobic structures in porous substrates
US9266105B2 (en) 2014-06-23 2016-02-23 Xerox Corporation System and method for forming bonded substrates
US9346048B2 (en) 2014-06-23 2016-05-24 Xerox Corporation Paper-based chemical assay devices with improved fluidic structures
US9415610B2 (en) * 2014-06-23 2016-08-16 Xerox Corporation System and method for forming hydrophobic structures in a porous substrate
US9480980B2 (en) 2014-06-23 2016-11-01 Xerox Corporation Apparatus for producing paper-based chemical assay devices
US9403358B1 (en) 2015-04-17 2016-08-02 Xerox Corporation System and method for forming hydrophobic structures in a hydrophilic print medium

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Also Published As

Publication number Publication date
FI74066B (en) 1987-08-31
ATA376185A (en) 1989-09-15
DE3600033A1 (en) 1986-07-10
FI860051D0 (en)
FI860051A (en) 1986-07-05
SE8600005D0 (en) 1986-01-02
CA1264588A (en) 1990-01-23
SE466757B (en) 1992-03-30
US4606264A (en) 1986-08-19
FI860051A0 (en) 1986-01-06
CA1264588A1 (en)
SE8600005L (en) 1986-07-05

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